Passive energy absorbers are utilized in a wide variety of application on a vehicle to absorb the impact energy from a collision and manage crash energy and the resultant deformation of the vehicle. An energy absorber may be included as part of a bumper assembly, a door beam, an interior bolster, an arm rest, or the like. A bumper assembly is one example of an energy absorber that is subject to many tests.
One example of a test of a bumper assembly is the low velocity bumper impact test in which an impactor that is between 0.4-0.6 meters wide and having a mass equal the vehicle curb weight and with a speed of the impact of 4 kpm. The purpose of this test is to minimize axial deformation and thereby minimize damage to the bumper and other structures rear of the bumper.
Another example of a test of a bumper assembly is an RCAR association test that measures the damage to a vehicle in which an impactor has a width equal to about 40% of the width of the bumper and having a mass equal the vehicle curb weight and with a speed of the impact of 15 kph. The purpose of this test is to limit axial deformation so that it is contained within the energy absorber to minimize vehicle front end damage.
Another example of a test of a bumper assembly is a pedestrian leg impact test that measures the extent of cushioning provided for an impact with a pedestrian's leg. The extent of cushioning is measured in an impact with a pedestrian leg impactor having a width of 75-90 mm at the widest point and having a mass of about 13.8 kg and with a speed of the impact of 40 kph. The purpose of the test is to test the ability of the energy absorber to minimize leg injuries by reducing the impact force through a greater degree of deformation.
Conventional energy absorbers may fail some of the above test but pass the other tests because the required stiffness to pass some tests necessitates failure in the other tests that require compliance.
This disclosure is directed to solving the above problems and other problems as summarized below.